1. Field of the Invention
The invention relates to the field of air handling and more particularly to externally attached cabinets and their apparatus for filtering, heating, cooling and dehumidifying air within equipment enclosures.
2. Background Information
Control of the climate or environment within equipment enclosures is known and is commonly accomplished with an air conditioning system. The air conditioning system is either part of the building support equipment or it is attached to the exterior of the electrical equipment enclosure to provide conditioned air to the enclosure. In the field, most air conditioning systems recirculate the air within the equipment enclosure and do not allow significant mixing of outside air with inside air. In temperate regions, the air conditioning system typically removes humidity from the recirculated air at the same time it cools the air within the electrical equipment enclosure. The systems may also include filters to remove particulate in the recirculated air. In cold areas, the air conditioning system may alternatively heat the recirculated air and/or add moisture. When the systems heat the air, heating is normally accomplished with a heat pump, which is able to perform both heating and cooling functions.
An objective when controlling the recirculated air environment within the electrical equipment enclosure is to create and maintain an environment inside the enclosure that is different than the environment outside the enclosure. This objective is economically accomplished by recirculating the air and by reducing or eliminating the mixing of inside and outside air. Seals between inside and outside help eliminate mixing.
U.S. Pat. No. 5,657,641, issued to Cunningham et al. (the ""641 patent), the disclosure of which is hereby incorporated by reference, discloses an apparatus to create and maintain an environment within an equipment enclosure. As described in the ""641 patent, it is known to attach a cabinet to the exterior of an equipment enclosure, the cabinet containing heating, cooling and/or filtering equipment. The heating, cooling and/or filtering equipment typically includes blowers, a compressor, a condenser coil and an evaporator coil, and ducting to direct air flows through the condenser coil and evaporator coil to heat and cool the respective air streams. It is also common for condensate to form on the evaporator coil, which may drip from the evaporator coil into some form of collection pan. Depending on the application, the condensate is either drained from the cabinet or evaporated within the cabinet.
In most applications, introduction of condensate from the air conditioning cabinet into the electrical equipment enclosure is damaging and potentially dangerous. For many of these applications, condensate discharge either inside the cabinet or outside the cabinet is unacceptable. Thus, it is appropriate and advantageous to ensure that all condensate is evaporated within the cabinet during operation. Therefore, configurations that minimize or avoid the possibility of condensate entering into the electrical equipment enclosure are appropriate and advantageous.
When the cabinet is mounted on the exterior of the equipment enclosure it is subject to any local weather effects, such as rain, sleet, snow and wind. It is therefor necessary for the cabinet and enclosure to have suitable connections and seals. When securely connected to the enclosure, the cabinet and enclosure should not be separated in high winds, and precipitation should not enter either the cabinet or enclosure. Though it is common for the air conditioning cabinet to be mounted on the side of the electrical equipment enclosure, it is also possible to mount the cabinet on the top of the enclosure. Depending on the mounting location, the internal orientation of air conditioning equipment in the cabinet changes.
When an air conditioning cabinet is externally mounted to the equipment enclosure, the construction quality of the cabinet is visible. The connection of the air conditioning cabinet to the equipment enclosure is also visible. Previously known mounting configurations include an external flange arrangement such as disclosed in the ""641 patent. In the flange arrangement disclosed in the ""641 patent, screws or bolts attaching the cabinet to the enclosure are exposed to view and the environment. This exposed flange mounting configuration can be less attractive. Additionally, screws or bolts may corrode unless they are corrosion resistant. Mounting configurations that provide a pleasing and uncluttered appearance, are advantageous.
Apparatus and methods for air handling that address these and other problems are needed.
In one aspect, an air handling apparatus comprises a mounting plate that is adapted to attach to an electrical equipment enclosure. A cabinet is adapted to connect to the mounting plate and also adapted to contact the enclosure. At least one mounting bracket cooperates between the mounting plate and the cabinet to thereby connect the cabinet to the mounting plate. At least one latching screw moves the cabinet relative to the mounting plate in a combined direction toward the enclosure and along the enclosure. A compressible seal between the cabinet and the enclosure provides an environmental seal against weather effects. After the movement, the mounting plate and mounting bracket are substantially concealed by the cabinet. This advantageously presents a pleasing non-industrial appearance.
In another aspect, individual panels are joined to each other with a mounting bracket, comprising a combination of hooks and slots. A compressible seal between the panels provides an environmental seal against weather effects after the panels are joined.
In another aspect, an injection molded plastic grill for the apparatus comprises a combination of guide plates, diverter plates and blocking plates, which are joined to each at varying angles. The different plates turn an airflow that exits the apparatus to a more horizontal direction. The different plates also stiffen the grill.
In another aspect, an air handling apparatus comprises an internal circulation region of the apparatus, with an evaporator coil horizontally disposed within the internal circulation region. A condensate pan is also within the internal circulation region and disposed below the evaporator coil. There is an external circulation region of the apparatus, and a condensate evaporator pan within the external circulation region. The condensate evaporator pan is disposed below the condensate pan. A condensate passage connects the condensate pan with the condensate evaporator pan. The internal circulation region is substantially sealed from the external circulation regions except for the condensate passage. A condenser blower within the external circulation region is disposed below the condensate evaporator pan. Air circulated by the condenser blower in the external circulation region aids in evaporation of condensate in the condensate evaporator pan. This advantageously eliminates condensate without a liquid discharge from the cabinet.
In another aspect, an air handling apparatus comprises an internal circulation region of the apparatus with an evaporator blower disposed within the internal circulation region. An evaporator coil is disposed within the internal circulation region and below the evaporator blower. The evaporator coil is oriented in a substantially horizontal direction, the orientation of the evaporator coil allowing airflow within the internal circulation region to enter the evaporator coil at a lower surface and exit the evaporator coil at an upper surface. A condensate pan within the internal circulation region is disposed below the evaporator coil. An external circulation region of the apparatus is substantially sealed from the internal circulation region. A condenser blower is within the external circulation region and is disposed below the condensate pan. A condenser coil is within the external circulation region and is disposed below the condenser blower. A compressor within the external circulation region is disposed below the condenser coil. The orientation of evaporator blower, evaporator coil, condensate pan, condenser blower, condenser coil and compressor is one above the other. The velocity of airflow through the evaporator coil as a result of the evaporator blower is sufficiently low that any condensate formed on the evaporator coil drips into the condensate pan. This advantageously provides a compact and visually pleasing cabinet while reducing the probability that condensate will enter the electrical equipment enclosure.
The foregoing specific objects and advantages of the invention are illustrative of those which can be achieved by the present invention and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, the objects and advantages of this invention will be apparent from the description herein or can be learned from practicing the invention, both as embodied herein or as modified in view of any variations which may be apparent to those skilled in the art. Accordingly, the present invention resides in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.